Though Letterman did his usual, half-hearted introductory joke about the album cover (which didn't bode so well for Joanna Newsom last December), Adele clearly knocked his socks off. The toothsome chantress beguiled the audience last night with a strong rendition of "Rolling in the Deep." Letterman even tried to produce a soulful growl of approval, but his "fantastic" was a bit more convincing.